Steam-engine indicator attachment



(No Model.)

J. R. MITCHELL. STEAM ENGINE INDICATOR ATTACHMENT.

Patented Apr. 10. 1888.

UNITED STATES PATENT OFFICE.

JOSEPH RAMSDEN MITCHELL, OF OAKLAND, CALIFORNIA.

STEAM -ENGINE. INDICATOR ATTACHMENT.

, I SPECIFICATICN forming part of Letters Patent No. 380,918, datedApril 1888.

Application filed November 8, 1886. Serial No.2l8,333. (No model.)

To a ZZ whom, it may concern.-

' Be it known that I, JOSEPH RAlVISDEN MITCHELL, of the city of Oakland,county of Alameda, and State of California, have invented an ImprovementinIndicator Attach ments; and Ihereby declare the following to be afull, clear, and exact description thereof.

My invention relates to the class of indi cators for engines; and myinvention consists, broadly, in a novel connection with the cardbearingcylinder of the indicator, whereby the limits of oscillation of saidcylinder are shifted to provide for consecutive separate diagrams on theindicator-card, and, further, in such a connection as will effect saidshifting at the time when the pencil describing the diagram is movingupon the exhaust -line, or line parallel to the atmospheric line,whereby any distortion of the diagram is prevented.

My invention consists, particularly, in a cord for effecting the usualpartial rotation of the cylinder, and which is so connected as to alterits len th, whereby the cylinder is given or allowed to have anadditional movement to vary the position of the diagrams on the card,and, finally, in the novel connection of the cord, whereby its length isautomatically altered, all of which I shall hereinafter fully describe.

My invention has for its object the making of distinct and separateconsecutive diagrams on the same card. I

Referring to the accompanying drawings, Figure 1 is an elevation showingthe attachment in connection with the cylinder of the indicator, thecard 1 of which, and also the card 2 below, for the sake of showing thediagrams,

- being shown extended instead of wound around the cylinder in normalposition. Fig. 2 is an elevation showing the change in the position ofparts for changing the time of shortening the connecting-cord from thebeginning of, say, the forward stroke to the beginning of thereturn-stroke.

The indicator proper, which may be of any of the ordinary types, issufficiently illustrated herein by its cylinder P, to which is attachedthe card 1, which, though normally encircling the cylinder, is hereshown extended, for the purpose of exhibiting the independentconsecutive diagrams 1 2 3 4 5, which are the result of my attachment. 4

It will of course be understood that the cylinder P, as usual, isinfluenced by a spring (not shown.) tending to turn it back.

A is a frame or standard, to be secured to the engine, and to which thelever B is pivoted by pin or stud 0, upon which it vibrates, said leverbeing supposed to be connected with the cross-head of the piston-rod, asusual, whereby it is operated.

L is a cord, one end of which is wound on the end of cylinder P. Inordinary cases the other end of the cord is attached directly to thelever B, whereby, as said lever moves over in the direction shown byarrow 1, the cord L turns the cylinder, the pencil meanwhile describingthe diagram on the indicator-card, and as the said lever returns thecylinder turns back under the influence of its spring, and keeps thecord taut. In this operation it will be seen that as the limits ofoscillation of the cylinder are unvarying, the diagrams are more or lesscoincident, and an attempt to describe several simply results inconfusion of lines.

- I propose by my invention to shift each time the limits of thecylinders oscillation, so as to avoid coincident diagrams, and in theirstead to make a series of independent consecutive diagrams, as shown by1, 2, 3, 4, and 5. Instead, therefore, of maintaining a given length ofcord, L, as is usually done, I provide for such a connection of saidcord that at each effort it shall have its length varied, (here shown,for example, as shortened,) and while I do not wish to confine myself,as far as the principle of my invention is concerned, to the connectionhere shown and described, such connection is sufficient for thisapplication.

In the lever B is mounted a drum, H, to which the cord L is attached,and from which it passes down and is guided properly to the cylinder P.Upon the drum is a ratchet, G, which is engaged by a retaining-pawl, K,and by an actuating'pawl, F; This latter pawl is pivoted in thelower endof an elbow or bellcrank lever, B, .fulcrumed at D and having in itsupper end a stop-screw, M, which in some cases, as .in Fig. 2, is setdown to impinge on the head N, formed on the upper end of lever B.

The operation is as follows: In Fig. 1 when the leverB is moved in thedirection of arrow 1 the immediate effect is through the engagement ofthe ratchet G with the actuating-pawl F to turn said ratchetslightly-say one toothso that the drum II is partially rotated, which,winding up, shortens the cord L, thus providing for a more extendedmovement of the indicator-cylinder P at the start than it would havefrom the movement of lever B alone. The retaining-pawl K holds the drumand cord against the return of the cylinder acting under its spring. Thesame thing occurs on the forward movement again, the cord Lbeingshortened up once more, so that the limits of the cylinders oscillationare constantly varied, which enables it to present the card it carriesin various positions to the pencil and providing for the series ofconsecutive diagrams 1, 2, 3, 4, and 5, card 1. Now, as the change oflength of cord L must take place on the forward strokes when the engineis running ahead and on the back-strokes when running back, I effectthis change by the stop'screw M, which, as shown in Fig. 2, is set downto contact with the head N of lever B. In this figure the lever B issupposed to be starting in the direction of arrow 2, and as at startingthe contact of the head N and stop-screw M holds the lever E to movewith the lever B, the e11- gagement of the ratchet G with the pawl F ofsaid lever turns said ratchet and effects the shortening of the cord L,with the result as before described, the only difference being in thechange of the time when the cord is shortened and in the direction ofthe diagrams l, 2, 3, 4, and 5, as shown in card 2. In either case itwill be seen that as the shortening takes place right at the start ofthe stroke there will be no distortion in the diagrams, as the changetakes placewhen the pencil describing the dia; grams is moving upon theexhaust-line shown in cards 1 and 2 by the figure 8. Though I havedescribed the shifting of the cylinders limits of oscillation as takingplace through the shortening of cord L, it is apparent that byperiodically lengthening the cord the same result may be had, as thecylinders spring will turn it back to a new position.

By my invention I can obtain a series of consecutive diagrams separateand distinct, and giving with unfailing accuracy the performance of thegovernor, showing at a glance whether there is any irregular movement,and also presenting at one view many other points desirable to be known,and which can only be ascertained by a series of consecutive diagrams.By the use of two indicators-one at each end of the cylinder-a series ofdiagrams following consecutively from each end of the cylinder canbeobtained, showing thirty or forty revolutions of the engine, all ontwo cards, which can be taken at one view. I can by this attachment takea number of diagrams on one card at intervals of several revolutions byturning the drum H and ratchet Gr by hand. I take a diagram, then turnthe ratchet-wheel a space of two or three or any desirable number ofteeth, then take another diagram, and continue until the end of the cardis reached. 1 thus have presented on one card the performance of theengine under different loads or arrangement of the valves. I save time,also, by the use of my attachment.

By the old method only two or three diagrams of varying pressures can betaken without becoming hopelessly mixed and blurred, and no consecutiveaction of the governor during a number of revolutions can be obtained.

I obviate these difficulties and can obtain a correct record of thegovernors action through a number of revolutions, thereby giving a muchmore ready and accurate means of ascertaining the-performance andconditions under which the machine is working.

The device for changing the length of the cord can be stopped or startedat pleasure with the machine running at full speed.

Having thus described my invention, what I claim as new, and desire tosecure by Letters Patent, is-

1. An indicator for determining the performance of an engine or othersimilar machine, said indicator having a card on which the diagram istraced, in combination with the vibrating lever receiving its motionfrom said engine or other machine, and a conncctlon for I varyingthelength of connection between said lever and the indicator, whereby aseries of consecutive separate diagrams are made on thecard,-substantially as described.

2. In combination with an indicator-cylinder for carrying a card onwhich a diagram is traced to show the performance of an englne or othermachine, a vibrating lever,and a connection between said lever and theindicatorcylinder, whereby the cylinders limits of oscillation areshifted to provide for making a series of consecutive separate diagramson the indicator-card, substantially as described.

3. The vibrating lever deriving motion from the engine or other machine,and the card-bearing cylinder of the indicator, in combination with acord and the vibrating lever attached thereto, so as to vary the lengthof connection when the lever moves, whereby the cylinders limits ofoscillation are shifted to provide for a series of consecutive separatediagrams on the indicator-card, substantially as described.

4. The combination, with an indicator-cylinder for carrying a card onwhich a diagram is to be traced to show the performance of an engine orother machine, and a vibrating lever deriving motion from said engine ormachine, of a cord connecting the lever with the indicator-cylinder,whereby the limits of oscillation of said cylinder are shifted toprovide for making a series of consecutive separate diagrams on theindicator-card, substantially as described.

5. The combination,with the vibrating lever deriving motion from theengine or other machine,and the card-bearing cylinder of theindicator,of a cord attached at one end to the cylinder and a connection betweenits other end and the vibrating lever,whereby its length is varied atthe beginning of the movement of ratchet as thelever moves and turningit partially, substantially as described.

7. The combinatiomwith the cord, the indicator-cylinder, the vibratinglever, and the w means for shortening said cord,f0r the purposedescribed, and holding it, of a drum carried by the lever and to whichone end of the cord is attached, a ratchet on the drum, a pawl engagingthe ratchet as the lever moves and turning it partially, and aretaining-pawl for holding it to the position turned,substantially asdescribed.

8. The combination,with the cord, the indicator-cylinder, the vibratinglever, and the means for shortening said cord at the begin- 'ning ofeither stroke'of thelever, and for the purpose described, of a drumcarried by the 3c lever and to which one end of the cord is attached; aratchet onthe drum, a retainingpawl engaging the ratchet, anactuating-pawl for turning it, a pivoted lever carrying said pawl, and aconnection between said pawl- 5 lever and the main vibrating lever,whereby the engagement of its pawl with the ratchet is varied as totime, substantially as described.

In witness whereof I have hereunto set my hand.

JOSEPH RAMSDEN MITCHELL.

Witnesses:

S. E. MITCHELL, S. A. TRAGO.

